Why mysql_store_result() Sometimes Returns NULL After mysql_query() Returns Success
It is possible for mysql_store_result() to return NULL following a successful call to mysql_query(). When this happens, it means one of the following conditions occurred:
- There was a
malloc()failure (for example, if the result set was too large). - The data could not be read (an error occurred on the connection).
- The query returned no data (for example, it was an
INSERT,UPDATE, orDELETE).
You can always check whether the statement should have produced a nonempty result by calling mysql_field_count(). If mysql_field_count() returns zero, the result is empty and the last query was a statement that does not return values (for example, an INSERT or a DELETE). If mysql_field_count() returns a nonzero value, the statement should have produced a nonempty result. See the description of the mysql_field_count() function for an example.
You can test for an error by calling mysql-error() or mysql_errno().